2 plastic or metal bowls (do not use glass, ever) (recommended size: 2 – 3 quart)
1 very sturdy spoon (wood works great, metal bends and plastic breaks)
1 vacuum insulated container (dewer or thermos)
2 liters of liquid nitrogen
Cloth gloves covered with rubber gloves
Safety goggles
Optional: dry ice (solid carbon dioxide)
Procedure
Mix half & half, sugar, vanilla and food coloring in one of the bowls.
Pour a small amount (about 1-2 cups) of the mixture into the other bowl. Add liquid nitrogen slowly, while stirring quickly, until the ice cream reaches the desired consistency. Dispense this amount and repeat.
Do not try to make too big of a batch at once, and do not use too deep a bowl. If the boiling nitrogen cannot escape quickly enough, it will cause the ice cream to froth, leading to a large, sticky spill! (Just ask Charlie). Start with small batches, and work up to larger ones as you go.
Safety
1. Liquid Nitrogen temperature is -195.79 °C or -320.42 °F and is consequently dangerous for that reason. It is the substance used by physicians to freeze of warts so it will damage the skin. Preventative measures include putting distance between the preparation table and the audience and wearing safety goggles, gloves and closed-toes shoes.
2. Liquid nitrogen is in fact a liquid and can soak into cloth. It is therefore recommended that plastic gloves be worn over cloth gloves for maximum protection.
3. If a Liquid Nitrogen spill occurs, clear the area of the spill and allow it to evaporate. The gas does not pose a major risk (nitrogen is already 78% of the air we breathe) if the experiment is performed in a room comparable in size to an average classroom.
4. Liquid Nitrogen should not be stored in the passenger compartment of a transportation vehicle.
5. Glass bowls should never be used with liquid nitrogen. They will break.
6. Dry Ice temperature is -78.5 °C or -109.3 °F and can cause damage to skin. The same precautions should be used in the handling of dry ice as with Liquid Nitrogen. Dry ice will also sublime to form carbon dioxide gas, which in a sufficiently ventilated area, should not be a danger.
Discussion Topics
Food Science in the kitchen is something you can enjoy at home with your parents. Mixing foods with specific tastes can result in exciting new flavors.
Making Ice Cream: A Lesson in Food Science and Changes of State
(Good for up to 25 kids)
Recipe
Equipment
Procedure
Safety
1. Liquid Nitrogen temperature is -195.79 °C or -320.42 °F and is consequently dangerous for that reason. It is the substance used by physicians to freeze of warts so it will damage the skin. Preventative measures include putting distance between the preparation table and the audience and wearing safety goggles, gloves and closed-toes shoes.
2. Liquid nitrogen is in fact a liquid and can soak into cloth. It is therefore recommended that plastic gloves be worn over cloth gloves for maximum protection.
3. If a Liquid Nitrogen spill occurs, clear the area of the spill and allow it to evaporate. The gas does not pose a major risk (nitrogen is already 78% of the air we breathe) if the experiment is performed in a room comparable in size to an average classroom.
4. Liquid Nitrogen should not be stored in the passenger compartment of a transportation vehicle.
5. Glass bowls should never be used with liquid nitrogen. They will break.
6. Dry Ice temperature is -78.5 °C or -109.3 °F and can cause damage to skin. The same precautions should be used in the handling of dry ice as with Liquid Nitrogen. Dry ice will also sublime to form carbon dioxide gas, which in a sufficiently ventilated area, should not be a danger.
Discussion Topics
Adapted from Bevin C. Daglen 2005
Links:
The Institute for Liquid Nitrogen Ice Cream Experimental Studies (one of Charlie's old professors)